Tissue-specific expression of the chicken adipose differentiation-related protein (ADP) gene

Adipose differentiation-related protein gene (ADP) plays an important role in controlling lipid accumulation in mammals. It may also affect lipid deposition in birds. However, the molecular mechanism of its actions in birds remains unknown. In the present study, the coding sequence of ADP cDNA for Chinese native breed Sichuan Mountainous Black-bone chicken (MB) was first cloned from abdominal fat using reverse transcription-PCR (RT-PCR). This putative MB ADP cDNA (1,881 bp) encodes an open reading frame of 438 amino acids (AA) and shares high AA sequence identity with that of red jungle fowl (99%), duck (92%), house mouse (70%), human (70%), chimpanzee (70%), pig (70%), domestic cow (69%) and domestic sheep (68%). Further analysis using bioinformatics shows the deduced MB ADP protein has the typical characters of PAT (Perilipin, Adipophilin and Tip47) family. Quantitative real-time PCR (qRT-PCR) analysis revealed that ADP expresses in chicken leg muscle, whole brain, heart, liver, pectoralis muscle, abdominal fat and subcutaneous fat. Ontogenetic expression studies shows ADP expression levels in abdominal fat, subcutaneous fat and pectoralis muscle were prior to that in leg muscles at posthatch day (P) 84. But, its levels in abdominal fat and subcutaneous fat were less than that in leg muscles at P28, 42, 56 and 70, respectively. The ADP expression levels in subcutaneous fat and abdominal fat were stable from P28 to P70 and both were less than their counterparts at P84. However, it changed greatly in pectoralis muscle, liver, brain, heart and leg muscle at all points. Patterns of ADP expression suggest that ADP plays an important role in fat development, but further study is needed to reconfirm its function in a large population and in other breeds with different genetic backgrounds.